Calcium aluminate clinker as a refractory aggregate with and without barium addition and use thereof

ABSTRACT

The present invention provides for a refractory aggregate composition comprising an improved calcium aluminate clinker having the formula C n A x  wherein C is calcium oxide and A is aluminum oxide, wherein n is an integer from about 1 to about 12, wherein x is an integer from about 1 to about 24, and wherein said clinker has from zero to less than about fifty weight percent C 12 A 7 , and including a source of barium that is substituted for calcium in said calcium aluminate clinker. Analogs, derivatives and hydrates of the improved calcium aluminate clinker are provided. A refractory composition and a sprayable refractory composition are disclosed comprising the improved calcium aluminate clinker. A method for improving the insulating character and/or penetration resistance of a liner in contact with molten aluminum in an aluminum manufacturing process or during aluminum transport is provided.

BENEFIT OF PRIOR PATENT APPLICATIONS

This utility patent application is a divisional application of andclaims the benefit of co-pending prior U.S. patent application Ser. No.12/891,262, filed on Sep. 27, 2010, which is a divisional application ofU.S. Utility patent application Ser. No. 11/899,128, filed on Sep. 4,2007, now U.S. Pat. No. 7,824,464 (granted Nov. 2, 2010), which claimsthe benefit of U.S. Utility patent application Ser. No. 10/924,713,filed on Aug. 24, 2004, now U.S. Pat. No. 7,368,010 (granted May 6,2008) which claims the benefit of U.S. Provisional Patent ApplicationSer. No. 60/497,998 (now expired), filed Aug. 25, 2003, entitled“Calcium Aluminate Clinker As A Refractory Aggregate With And WithoutBarium Addition And Use Thereof” having the same named applicant asinventor, namely, Kenneth A. McGowan. The entire contents of U.S.Provisional Patent Application Ser. No. 60/497,998, U.S. Utility patentapplication Ser. No. 10/924,713, U.S. Utility patent application Ser.No. 11/899,128, and U.S. patent application Ser. No. 12/891,262 areincorporated by reference into this divisional utility patentapplication.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The use of calcium aluminate clinker as a refractory aggregate in shapesand castables. The present invention provides an improved refractoryaggregate based on Ca0.Al₂0₃ clinker (hereinafter referred to as “CA”clinker and designated by the following equation C_(n)A_(x), whereinpreferably n is an integer from about 1 to 12 and x is an integer fromabout 1-24) and C_(n)A_(x) hydrate phases and analogs or derivativesthereof including those based on barium substitution for calcium orbarium additions resulting in calcium substitution after chemicalreaction and/or heat treatment, all of which are referred to herein asCA clinker. Refractory materials based on aggregate compositions havingthese phases singularly or combined, and exclusive of C₁₂A₇ as a majorphase, are provided in the present invention.

2. Description of the Background Art

Lafarge Calcium Aluminates Inc. (Maryland, USA) markets a calciumaluminate clinker as an aggregate available under their “r50” tradename. This clinker known by those skilled in the art is about 52%alumina and is dense. The presence of a relatively large amount of C₁₂A₇causes the LaFarge Calcium Aluminates, Inc.'s calcium aluminate clinkerto melt and the product is essentially fused with little or no porosity.Thus, this composition has little utility as a refractory aggregate. Thepresent invention provides a composition comprising a C_(n)A_(x) clinkerthat lacks significant amounts of C₁₂A₇ and that has the additionalbenefit of the presence of porosity and usefulness as a refractoryaggregate.

It is known in the refractory arts that the addition ofbarium-containing materials impart a penetration resistance to materialsin contact with molten aluminum. In another embodiment of the presentinvention, compositions are provided wherein barium is substituted intothe CA clinker matrix of the present invention resulting in BA₆, BC₂A₄and the other analogs that increase the performance of the product andresist aluminum penetration to a great degree.

A primary area of application for the compositions of the presentinvention is in contact with molten aluminum. Because aluminum has sucha low viscosity in the molten state, it easily penetrates the refractoryused to contain it. This causes the refractory to wear. In addition,penetration of the refractory causes the freeze plane to move furtherinto the refractory lining thereby allowing molten aluminum to penetratefurther. Ideal materials are those that resist aluminum penetration andare insulating enough to have the freeze plane as close as possible tothe hot face or contact face of the refractory lining. Currenttechnology relies on the addition of penetration inhibitors that workeither by reducing the porosity of the refractory, which can result inmoving the freeze plane further into the lining, or by changing thewetting angle of the aluminum on the refractory. Well known examples ofthese penetration inhibitors are fluorospar and barium sulfate,respectively. Other ways of reducing penetration known by those skilledin the art involve the use of increasingly pure alumina as an aggregateand making this material as dense as possible to reduce open porosityand hence penetration. This increases the conductivity of the materialand pushes the freeze plane into the backup refractory lining in mosttypical configurations known by those skilled in the art.

Therefore, in spite of the background art, there remains a very real andsubstantial need for a refractory composition and a refractory aggregatecomposition having the improved calcium aluminate clinker, and asprayable and/or castable refractory composition, for use, such as forexample, but not limited to, as a refractory lining in the production ofmolten aluminum.

SUMMARY OF THE INVENTION

The present invention provides a refractory aggregate compositioncomprising a calcium aluminate clinker having the formula C_(n)A_(x)wherein C is calcium oxide and A is aluminum oxide, wherein n is aninteger from about 1 to about 12, wherein x is an integer from about 1to about 24, and wherein said clinker has less than about fifty weightpercent C₁₂A₇, and preferably less than about 10 weight percent. Inother embodiments of the refractory aggregate composition of thisinvention, as described herein, the aggregate includes a hydrate phaseof the C_(n)A_(x), analogs of the C_(n)A_(x), and derivatives of theC_(n)A_(x).

In another embodiment of the present invention, the refractory aggregatecomposition, as described herein, includes wherein barium is substitutedfor calcium in the calcium aluminate clinker.

In yet another embodiment of the present invention, the refractoryaggregate composition, as described herein, further comprises a sourceof barium. The refractory aggregate composition, preferably, includeswherein the barium source addition results in the formation of analogsand derivatives of said C_(n)A_(x) and optionally hydrates of saidC_(n)A_(x). More preferably, the refractory aggregate, as describedherein, includes wherein the barium is present in one or more phases asBaO, BA₆, and C₂BA₄, and combinations thereof.

In another embodiment of the refractory aggregate composition of thepresent invention as described herein, the alumina content of thecalcium aluminate clinker is greater than or equal to sixty eight weightpercent.

Another embodiment of the present invention provides for the refractoryaggregate composition, as described herein, further comprising a calciumaluminate cement.

An improved calcium aluminate clinker, is provided, of the type havingthe formula C_(n)A_(x) wherein C is calcium oxide and A is aluminumoxide, wherein n is an integer from about 1 to about 12, and x is aninteger from about 1 to about 24, the improvement comprising limitingthe concentration of a C₁₂A₇ phase to less than about fifty percentC₁₂A₇. Preferably, the improved calcium aluminate clinker includes oneor more of a hydrate phase of the C_(n)A_(x), includes analogs of theC_(n)A_(x), and includes derivatives of the C_(n)A_(x).

In another embodiment of this invention, the improved calcium aluminateclinker, as described herein, includes wherein barium is substituted forcalcium in the calcium aluminate clinker.

In another embodiment of this invention, the improved calcium aluminateclinker, as described herein, further comprising a source of barium.Preferably, the improved calcium aluminate clinker includes wherein thebarium source addition results in the formation of analogs andderivatives of the C_(n)A_(x) and optionally hydrates of the C_(n)A_(x).More preferably, the improved calcium aluminate clinker includes whereinthe barium is present in one or more phases as BaO, BA₆, and C₂BA₄, andcombinations thereof.

Another embodiment of the present invention provides a refractorycomposition comprising a refractory aggregate comprising a calciumaluminate clinker having the formula C_(n)A_(x), wherein C is equal tocalcium oxide, wherein A is equal to aluminum oxide, wherein n is aninteger from about 1 to about 12, wherein x is an integer from about 1to about 24, and wherein said calcium aluminate clinker has less thanabout fifty percent C₁₂A₇, and a calcium aluminate cement. Preferablythe refractory composition of the present invention, as describedherein, further comprises water in a sufficient amount to achieve acastable consistency. The refractory composition includes in otherembodiments the refractory aggregate compositions as described herein.The refractory composition, as described herein, includes wherein therefractory aggregate further comprises one or more of a reactivealumina, a calcined alumina, tabular alumina, and bubble alumina, and alightweight calcium alumina aggregate, and combinations thereof. In amore preferred embodiment, the refractory composition of the presentinvention further comprises a surfactant. In a more preferred embodimentof the refractory composition of the present invention, the refractorycomposition further comprises a fibrous material. In a most preferredembodiment of the present invention, the refractory composition furthercomprises a surfactant and a fibrous material. The refractorycomposition of this invention further comprises water in an amountsufficient to achieve a castable consistency.

Another embodiment of this invention provides wherein the refractoryaggregate composition and the calcium aluminate clinker, as describedherein, may be formed by sintering or by employing a fusion process.

Another embodiment of this invention provides a sprayable refractorycomposition comprising: (a) a pumpable first component comprising (i) arefractory composition, as described herein, comprising a refractoryaggregate comprising a calcium aluminate clinker having the formulaC_(n)A_(x), wherein C is equal to calcium oxide, wherein A is equal toaluminum oxide, wherein n is an integer from about 1 to about 12,wherein x is an integer from about 1 to about 24, and wherein thecalcium aluminate clinker has less than fifty percent C₁₂A₇, and acalcium aluminate cement, (ii) a dispersant, and water in an amountsufficient to achieve a pumpable consistency, and optionally (b) asecond component comprising a flocculating agent, wherein the secondcomponent is added to the first component for achieving installation ofthe sprayable refractory composition. The sprayable refractorycomposition, as described herein, includes wherein the refractorycomposition includes a hydrate phase of C_(n)A_(x), includes analogs ofC_(n)A_(x), and includes derivatives of C_(n)A_(x). The sprayablerefractory composition includes the refractory composition andrefractory aggregate composition as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a phase diagram that sets forth the CaO—Al₂O₃ system.C=CaO, A=Al₂O₃. The horizontal axis of FIG. 1 shows molecular formationsin the range up to the pure oxide of aluminum or Al₂O₃ on the right andpure CaO on the left. The numbers on the horizontal axis represent thepercent of Al₂O₃ present in the system.

FIG. 2 shows a more detailed description of the higher Al₂O₃ portion ofFIG. 1.

FIG. 3 shows the BaO—CaO—Al₂O₃ system containing BaO at 1250 degreesCentigrade.

FIG. 4 shows the BaO—CaO—Al₂O₃ system containing BaO at 1400 degreesCentigrade.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a calcium aluminate (CA) clinker withoutC₁₂A₇ as a major phase and further comprising Al₂0₃(A), CA (the discretecompound CaO—Al₂O₃, not to be confused with the CA clinker) and CA₂ asmajor phases. There can be other phases present in the clinker such as,for example, C₃A, C₂A₄, etc. Upon heating, the phases can form CA₆. Inany case, it is known that these phases, including the C₁₂A₇, naturallyresist penetration of molten aluminum, to a degree. In a preferredembodiment of this invention, the CA clinkers of the present invention,for example, but not limited to rotary kiln products, have otherbeneficial features, at alumina contents of about 68% and higher. First,the shape of the aggregate is rounded making it easier to create a freeflowing material. Also, because of the raw materials used to make theproduct, it tends to form into porous spheres. The porosity of thespheres becomes important if an insulation material, as a final product,is desired. When the aggregate is mixed with water, either in a castableproduct or shape mix, the surface of the aggregate becomes activated andbegins to form the expected hydrates. When the set reaction orprecipitation reaction occurs, the porosity of the aggregate is sealedoff and the aggregate is bonded together through surface contact. Thebenefit here is a more insulating material that resists penetration.When a large portion of the mix is the same type of material such as thecase would be in a castable, the resulting strength of the material isgreatly enhanced by the ability of the aggregate and the matrix to bondwith each other. In this case, the final material is a true monoliththat naturally resists penetration and is insulating in character due tothe sealed off porosity of the surface activated CA clinker. Because theCA clinker of the instant invention contains little or no C₁₂A₇, thematerial can be used at elevated temperatures consistent with aluminummanufacturing as well as other processes. The C₁₂A₇ is a low meltingphase that is common to cements having Al₂0₃ contents of 65% and lower.The more preferred CA clinker products of this invention are those withan Al₂0₃ content greater than sixty eight percent (68%) by weight in theclinker, as opposed to clinker co-ground with other materials such asadditional Al₂0₃. Preferably, the CA clinker of the present invention asdescribed herein comprises a concentration of Al₂O₃ greater than orequal to about sixty eight percent by weight (68% w/w) based upon thecurrent manufacturing process of calcium aluminate cements known bythose persons skilled in the art. This leads to a final composition ofthe present invention having a minimal C₁₂A₇ content. However, from thephase diagrams of FIGS. 1 and 2 it can be seen that upon the formationof the CA and CA₂ phases (near 68% Al₂O₃) and up to but not includingpure Al₂O₃, represents the ideal composition of the aggregate. That isCA, CA₂, C₃A₅, CA₆ and Al₂O₃ alone or in combination. The presentapplicant has discovered that CA clinkers containing C₁₂A₇ inappreciable amounts are undesirable. Thus, it will be appreciated bythose skilled in the art that the concentration of Al₂O₃ can be used asa guideline in determining the potential usefulness of the aggregate,however, the determining factor is limiting the presence of low meltingphases, in particular C₁₂A₇, that ultimately determines the usefulnessof the aggregate. The applicant of the present invention has found thatC₁₂A₇ concentrations of greater than about 3 molar % (Mol %, or M %)would not afford a useful aggregate for applications exceeding 1400degrees Centigrade but may prove useful at lower temperatureapplications.

Another embodiment of this invention provides the CA clinker compositionas described herein and wherein the composition further includes theaddition of a source of barium (added in a variety of forms such as thecarbonate or sulfate salts). If the barium exists in the proper ratiowith the Ca0(C) and the Al₂0₃ (A) one can form BA₆, B₃A, BA, and BC₂A₄(where B=BaO) with temperature. These are analogs of CA₆, C₃A, and CA,while BC₂A₄ is a derivative (FIG. 3 and FIG. 4). The presence of thesephases greatly enhances the ability of the product to resist penetrationby not only changing the contact angle of the aluminum, but also forminga solid solution distributed equally throughout the matrix. This issignificantly different than the heterogeneous mixtures currenttechnologies have with barium sulfate additions.

FIG. 1 shows a phase diagram that sets forth the CaO—Al₂O₃ system. Thehorizontal axis of FIG. 1 shows molecular formations in the range up tothe pure oxide of aluminum or Al₂O₃ on the right and pure CaO on theleft. The numbers on the horizontal axis represent the percent of Al₂O₃present in the system. The resulting solid phases are shown in the boxesset forth in FIG. 1. The temperatures (in degrees Centigrade) at whichthey are present, and stable, are shown on the vertical axis of FIG. 1.Note that the boxes of FIG. 1 containing the C₁₂A₇ solid begin to formliquids (area above the boxes at or near 1400 degrees Centigrade). Theeffect of the liquid is reduced strength and increased reactivity withthe surrounding environment, both of which are detrimental. The diagramof FIG. 1 shows pure CA present at about 68% Al₂O₃. From greater than orequal to about 68% Al₂O₃ compositions, formed phases are useful asaggregate. FIG. 2 shows a more detailed description of the higher Al₂O₃portion of FIG. 1.

FIGS. 3 and 4 show the BaO—CaO—Al₂O₃ systems of the present inventioncontaining BaO at 1250 degrees Centigrade and 1400 degrees Centigrade,respectively. BaO concentrations greater than zero percent that lead toformation of BA₆ and C₂BA₄ are beneficial. The presence of C₂BA₄ (higherconcentrations of BaO, via barium sulfate additions as the barium sourcein the following examples) results in improved penetration resistance.

The calcium aluminate (CA) clinker of the present invention as describedherein is a viable aggregate (as compared to a bond matrix) forrefractory products. The clinker may comprise all of the aggregate or aportion thereof. This does not include the use of the compound as adiscrete bonding matrix such as cement, where it is currently used in avariety of materials. The CA clinker is composed of C_(n)A_(x),C_(n)A_(x) hydrate, and Al₂0₃ phases. It will be appreciated by thosepersons skilled in the art that commercially available clinker haveseveral impurities present such as for example various iron oxides,silicon oxides, alkali, and alkaline earth compounds, etc. The presentapplicant has found that the purer the clinker the better will be itstemperature resistance, and preferably that the impurities are presentin concentrations less that 1%, the clinker will suffice as a useableaggregate. A typical commercially available clinker chemistry is shownhere in Table 1 below:

TABLE 1 Ingredient Avg. Wt. % Al₂O₃ 69.63 SiO₂ <0.8 Fe₂O₃ <0.5 CaO 28.12Others Combined <0.95It will be appreciated by those skilled in the art that the commerciallyavailable clinkers available as set forth in Table 1 will vary frombatch to batch and supplier to supplier due to raw material sourcing andother variations.

In the compositions of the CA clinker of the present invention, thepresence of C₁₂A₇ is limited as a minor constituent such thatcompositions comprise Al₂O₃ contents >68% in reference to the aggregateor clinker. As used herein, the term “major” means at least about 50% orgreater. As used herein, the term “minor” means less than about 50%.This does not include co-ground or blended materials whose chemistry canbe controlled by addition of discrete dilutents. This is importantbecause C₁₂A₇ is a low melting phase that limits the maximum operatingtemperature of the product if present in substantial amounts. Theapplication of the compositions of the present invention is limited toan operational temperature not exceeding about 1820 degrees Centigrade.At this temperature liquid phases form in the pure system. It should benoted that the product will not be a pure system due to impuritiespresent in the clinker.

The CA aggregate or clinker of the present invention may be a sinterproduct if porosity is desired or a fusion product if porosity is notdesired (including partial fusions as a means of controlling porosity).In some cases, such as aluminum contact, porosity is desirable in orderto give the working refractory lining greater insulating character. Thiscan move the freeze plane closer to the hot face and therefore allow fora thinner lining if desired. This in turn can allow for increasedproduction or transport capacity of aluminum, for example.

In the present invention the active surface of the aggregate allowsthese particles to participate in the bonding matrix, particularly atambient temperature. Although it is true that a cement bonding mix willbind almost any aggregate present, the aggregate itself retains itsindividuality. It is surrounded by a bond which holds it in place, butdoes not become part of that bond. The surface of the aggregate and thebonding matrix are essentially identical, in the case of a castable madeof the CA clinker of the present invention as the aggregate. Therefore,the aggregate and matrix become one and each component loses itsindividuality. Indeed no grain boundaries exist in the product made fromthe composition of the present invention identifying where the matrixends and the aggregate begins. Only the remaining porosity of theinactivated interior of the aggregate indicates where an independentgrain once existed. This results in the beneficial character of closedporosity, if desired, and increase strength of the true monolith. Thischaracter is retained as the material dehydrates with temperature.

The addition of barium to the compositions of the present inventionimproves the enhanced properties even further by reacting to formanalogs and derivatives of the C_(n)A_(x) and its hydrates, whichimprove penetration resistance by forming in-situ. FIG. 4 shows a phasediagram that sets forth the compounds of interest that are formed andtheir physical state at 1400 degrees Centigrade. FIG. 4 shows that atAl₂O₃ contents of greater than 68% and with the presence of BaO, Ba canexist in three different forms at this temperature: BaO, which changesthe contact angle of aluminum and allows for penetration resistance(current technology), BA₆ as a solid or solid solution, and C₂BA₄ as asolid or solid solution. The presence of all three of these compoundsimprove penetration resistance. In a more preferred embodiment of thisinvention, the compositions include areas of the phase diagram, whichcan lead to the formation of BA₆ and C₂BA₄, which greatly improve thepenetration resistance in comparison to the addition of BaO (typicallyas barium sulfate). In a preferred embodiment of this invention, theaddition or use of BaO in combination with the CA clinker of thisinvention for use as an aggregate is provided.

The following are examples of the compositions of the present invention.As used in the examples, CA clinker is as described herein; CAR60Alumina is calcined alumina and is commercially available from AlcanChemicals, Pittsburgh, Pa.; A-3000 FL Alumina is a reactive aluminawhich are ultrafine refractory material about 0.4 micron and 3.0 micronsaverage particle diameter size, respectively, and are greater than orequal to about ninety-nine (99) weight percent aluminum oxide materialand is commercially available from Almatis Chemicals, Leetsdale, Pa.;Type 153 fibers are fibrous materials commercially available as“HERCULON 153” polyfibers (Hercules, Incorporated, Wilmington, Del.);and the surfactant may be sodium tripolyphosphate (STPP) (UNIVARPittsburgh, Bunola, Pa.); Tabular Alumina is a refractory aggregatehaving greater than or equal to about ninety-nine (99) weight percentaluminum oxide commercially available from Almatis, Pittsburgh, Pa.;SLA-92 is a CA6 based lightweight (less than 120 pounds/cubic footdensity) calcium aluminate aggregate commercially available fromAlmatis, Pittsburgh, Pa. Bubble Alumina may be made by blowing a streamof high pressure air into molten alumina and is commercially availablefrom Almatis, Pittsburgh, Pa.; and Calcium Aluminate Cement is a 70percent alumina and 30 percent calcia cement commercially availableunder the trade name “Secar 71” from LaFarge Calcium Aluminates Inc.

Detailed Compositional Strategy Example “A”

The following EXAMPLE “A” demonstrates a detailed compositional matrixand the resulting physical properties of the resulting solid body.

Calcium Aluminate clinker of the following chemistry (reported on anoxide basis) was obtained for the study. The material was screened,sized and chemistry was determined on each fraction (see Table I).

TABLE I Fraction +10 m 10/28 m 28/65 m −65 m Oxide (concentration in Wt%) SiO₂ 0.44 0.29 0.22 0.25 Al₂O₃ 71.59 71.21 70.35 71.19 Fe₂O₃ 0.070.01 <0.01 0.01 CaO 27.38 28.08 29.02 27.95 MgO 0.27 0.22 0.21 0.31 Na₂O0.23 0.17 0.18 0.26 K₂O 0.01 0.01 0.01 0.02 P₂O₅ 0.01 0.01 0.01 0.01

Mineralogical Examination of these fractions showed the following:

+10 m 10/28 m 28/65 m −65 Compound Present CaAl₂O₄ (CA) M M M M CaAl₄O₇(CA₂) M M M M Ca₁₂Al₁₄O₃₃ (C₁₂A₇) m m t nd Ca₃Al₂O₆ (C₃A) nd nd nd ndCa₅Al₆O₁₄ (C₅A₃) nd nd nd nd Ca₂Al₁₂O₅ (C₂A) nd nd nd nd CaAl₁₂O₁₉ (CA₆)nd nd nd nd Ca₃Al₁₀O₁₈ (C₃A₅) nd nd nd nd CaO (C) t t t t Al₂O₃ (A) t tt t M = Major, m = minor, t = trace, nd = not detected

This chemistry and mineralogy is typical for a 70% alumina containing CAcement. CA cements containing greater than 70% alumina can be used. CAcement containing less than 70% alumina can also be used; however, mostcommercially available products have impurities, which increase inconcentration as the alumina content decreases. Common brands of 70%alumina containing CA cement are Almatis' CA14 product and Lafarge'sSecar 71 product.

The average open porosity of the CA aggregate is near 53% while the TSG(total specific gravity) averages 2.9 g/cm³ for the lot of aggregateused in this example. Note that batch to batch variation in theseproducts are expected due to the manufacturing process of the CAaggregate.

Composition Example “A”

Aggregate Wt % CA +10 m   15% CA 10/28 m   30% CA 28/65 m   10% CA −65 m  11% CA −325 m   7% A-2 alumina   8% A-3000 alumina   10% A-1000alumina   9% STPP (plus addition) 0.15%

24% by weight of water was added to give a vibration cast consistency.The material was cast into simple bars in order to determine modulus andcrushing strengths. The shape was stripped from the mold in 24 hours anddried at 110° C. (Centigrade). Finally, the shape was fired to atemperature of 1100° C. and allowed to reach thermal equilibrium. Theshape was allowed to cool and was tested. The results are as follows:

Apparent porosity=50%

Average pore size=40 microns

Cold crushing strength (ASTM C133)=34.5 MPa

Modulus of Rupture (ASTM C133)=9.3 MPa

Example #1

wt. % Mix Formulation CA clinker 70 Secar 71 15 CAR 60 Alumina 5A-3000FL Alumina 10 Plus Additions Type 153 fibers 0.1 Surfactant 0.1Water to cast 8.5

Example #2

wt. % Mix Formulation CA clinker 63.3 Secar 71 22.3 CAR 60 Alumina 4.4A-3000FL Alumina 10 Plus Additions Type 153 fibers 0.09 Surfactant 0.09Water to cast 7.5

Example #3

wt. % Mix Formulation CA clinker 70 Secar 71 25 CAR 60 Alumina 5 PlusAdditions Type 153 fibers 0.1 Water to cast 14

Example #4

wt. % Mix Formulation CA clinker 67 Secar 71 25 Barium Sulfate 8 PlusAdditions Type 153 fibers 0.1 Water to cast 13.5

Example #5

wt. % Mix Formulation CA clinker 85% Secar 71 15% Plus Additions Waterto cast 25%

Example #6

wt. % Mix Formulation CA clinker 50 Tabular Alumina 20 Secar 71 25 CAR60 Alumina 5 Plus Additions Water to cast 12

Example #7

wt. % Mix Formulation CA clinker 25 Bubble Alumina 45 Secar 71 25 CAR 60Alumina 5 Plus Additions Water to cast 11

Example #8

wt. % Mix Formulation CA clinker 71 Secar 71 25 Barium Sulfate 4 PlusAdditions Type 153 fibers 0.1 Water to cast 13.5

Example #9

wt. % Mix Formulation CA clinker 70 Calcium Aluminate 15 Cement CalcinedAlumina 5 Reactive Alumina 10 Plus Additions Water to cast 7

Example #10

wt % Mix Formulation CA Clinker 15 SLA-92 60 Cement 25 Plus AdditionsWater to cast 60

These examples show a variety of the compositions of the instantinvention having varying CA clinker concentrations. For instance Example#6 would result in a product with greater thermal conductivity comparedto Example #3 but Examples #7 nod #10 would represent a highlyinsulating material on comparison. Example #8 is a formulation thatresults in a product containing BA₆ while Example #4 shall form both BA₆and C₂BA₄. Example #5 is a highly porous material that has interestingfiltration properties.

These examples may be applied via a variety of known installationtechniques such as, but not limited to slip casting, vibration casting,pump casting, shape pressing, gunning, and shotcreting. For example, inshotcreting, as understood by those skilled in the art, adispersant/deflocculation system and optionally the use of aflocculating agent would be employed.

A sprayable refractory composition is provided in another embodiment ofthis invention comprising: (a) a pumpable first component comprising (i)a refractory composition comprising a refractory aggregate comprising acalcium aluminate clinker having the formula C_(n)A_(x), wherein C isequal to calcium oxide, wherein A is equal to aluminum oxide, wherein nis an integer from about 1 to about 12, wherein x is an integer fromabout 1 to about 24, and wherein said calcium aluminate clinker has lessthan fifty percent C₁₂A₇, and a calcium aluminate cement, (ii) aneffective amount of a dispersant, and water in an amount sufficient toachieve a pumpable consistency, and optionally (b) a second componentcomprising an effective amount of a flocculating agent, wherein thesecond component is added to the first component for achievinginstallation of the sprayable refractory composition. The sprayablerefractory composition includes wherein the refractory compositionincludes a hydrate phase of C_(n)A_(x). The sprayable refractorycomposition includes wherein the refractory composition includes analogsof C_(n)A_(x). The sprayable refractory composition includes wherein therefractory composition includes derivatives of C_(n)A_(x). In anotherembodiment of this invention, the sprayable refractory compositionincludes wherein a barium is substituted for calcium in the calciumaluminate clinker.

In yet another embodiment of this invention, the sprayable refractorycomposition, as described herein, includes wherein the refractorycomposition further comprises a barium oxide. More preferably, thesprayable refractory composition includes wherein the barium sourceaddition results in the formation of analogs and derivatives of theC_(n)A_(x) and optionally hydrates of the C_(n)A_(x). The sprayablerefractory composition, as described herein, includes wherein the bariumis present in one or more phases as BaO, BA₆, and C₂BA₄, andcombinations thereof. Most preferably the barium exists as BA₆ andC₂BA₄.

In another embodiment of the present invention provides wherein, thesprayable refractory composition, as described herein, includes whereinthe refractory aggregate further comprises one or more of a reactivealumina, a calcined alumina, a tabular alumina, and a bubble alumina, alightweight calcium aluminum aggregate (such as for example but notlimited to SAL-92 “type” aggregate), and combinations thereof.

In another embodiment of the sprayable refractory composition, thesprayable refractory composition, as described herein, further includeswherein the refractory composition further comprises a fibrous material.

As used herein, the term “effective amount” refers to that amount of asubstance necessary to bring about a desired result, such as forexample, the amount of water needed to achieve a consistency suitablefor installing the refractory sprayable composition, such as forexample, casting, spraying, pumping and combinations thereof.

With respect to the dispersant of the instant invention, it must be ableto disperse the constituents of the refractory composition when water isadded to the refractory composition. Combinations of dispersants aresometimes desirable depending on the specific constituents of therefractory composition. The dispersants employed in the presentinvention are those known to those skilled in the art. It will beappreciated by those skilled in the art that other additives may be usedin combination with the dispersants of the instant invention to affectthe rheology of the refractory composition. Such additives, include suchas for example but not limited to, boric acid or citric acid retarders,or lithium carbonate as an example of an accelerator.

With respect to the amount of water used in the refractory compositionof the present invention, an effective amount is needed to achieve acastable consistency of the constituents of the refractory compositionincluding the refractory aggregate and dispersant. Typically, the amountof water is from about 1 weight percent to about 80 weight percent foreach 100 weight percent of the constituent components of the refractorycomposition. The use of porous lightweight aggregate, such as SLA-92,may generally increase the water demand. Other examples of lightweightaggregates include, but are not limited to, bubble alumina, expandedclay, perlite, and pyrophylite, known by those skilled in the art.

With respect to the flocculating agent used in the instant invention,any suitable flocculating agent known to those skilled in the art thatis suitable for refractory use is may be used. For example, but notlimited to, the flocculating agents comprise at least one selected fromthe group of an alkali chloride, an alkaline-earth chloride, a calciumoxide, and a calcium aluminate.

These examples are not intended to limit the scope of the presentinvention as described herein. These examples are for purposes ofillustration and it will be evident to those persons skilled in the artthat numerous variations and details of the instant invention may bemade without departing from the instant invention as set forth herein.

I claim:
 1. A calcium aluminate clinker having the formula C_(n)A_(x)wherein C is calcium oxide and A is aluminum oxide, wherein n is aninteger from about 1 to about 12, and x is an integer from about 1 toabout 24, wherein the concentration of a C₁₂A₇ phase is less than about50% C₁₂A₇, and including a source of barium that is substituted forcalcium in the calcium aluminate clinker.
 2. The calcium aluminateclinker of claim 1 including a hydrate phase of the C_(n)A_(x).
 3. Thecalcium aluminate clinker of claim 1 including analogs of the C_(n)A_(x)that are BA₆, B₃A, and BA.
 4. The calcium aluminate clinker of claim 1including derivatives of the C_(n)A_(x) that are BC₂A₄ and C₂BA₄.
 5. Thecalcium aluminate clinker of claim 1 further comprising a barium oxide.6. The calcium aluminate clinker of claim 5 wherein the barium oxideaddition results in the formation of analogs of the C_(n)A_(x) that areBA₆, B₃A, and BA and derivatives of the C_(n)A_(x) that are BC₂A₄ andC₂BA₄ and hydrates of the C_(n)A_(x).
 7. The calcium aluminate clinkerof claim 1 wherein the barium is present in one or more phases as BaO,BA₆, and C₂BA₄, and combinations thereof.
 8. The calcium aluminateclinker of claim 7 wherein the barium is present in one or more phasesas BA₆ and C₂BA₄.
 9. The calcium aluminate clinker of claim 1 whereinthe alumina content of the calcium aluminate clinker is greater than orequal to 68 wt %.
 10. A cast product or a shaped pressed productcomprising a refractory composition comprising a refractory aggregateconsisting essentially of a calcium aluminate clinker having the formulaC_(n)A_(x), wherein C is equal to calcium oxide, wherein A is equal toaluminum oxide, wherein n is an integer from about 1 to about 12,wherein x is an integer from about 1 to about 24, and wherein thecalcium aluminate clinker has from zero to less than about 50 wt %C₁₂A₇, and wherein greater than 98 weight percent of the calciumaluminate clinker having a particle size ranging from 325 mesh to +10mesh.
 11. The product of claim 10 wherein the refractory aggregate isporous.
 12. The product of claim 10 wherein the refractory aggregate isformed by sintering.
 13. The product of claim 10 wherein the refractoryaggregate has no porosity.
 14. The product of claim 10 wherein therefractory aggregate is formed by a fusion process.
 15. The product ofclaim 10 wherein the refractory composition includes wherein barium issubstituted for calcium in the calcium aluminate clinker.
 16. Theproduct of claim 10 wherein the refractory composition comprises asource of barium, wherein the barium source is present in one or morephases as BaO, BA₆, and C₂BA₄, and combinations thereof.
 17. The productof claim 16 wherein the refractory composition comprises the source ofbarium that is present in one or more phases as BA₆ and C₂BA₄.
 18. Theproduct of claim 10 further comprising a barium oxide.
 19. The productof claim 10 wherein the refractory composition comprises one or more ofa alumina, a calcined alumina, a tabular alumina, and a bubble alumina,and combinations thereof.
 20. The product of claim 10 wherein therefractory composition comprises one or more lightweight aggregates. 21.The product of claim 20 wherein the lightweight aggregate is one or moreof a bubble alumina, an expanded clay, a perlite, and a pyrophilite, andcombinations thereof.
 22. The product of claim 10 wherein the refractorycomposition comprises at least one of a surfactant, and a fibrousmaterial, and combinations thereof.
 23. The product of claim 10 whereinthe refractory composition comprises a calcium aluminate cement.
 24. Theproduct of claim 10 wherein the refractory composition comprises one ormore of a set retarder, and a set accelerator, and combinations thereof.25. The product of claim 10 wherein the refractory composition comprisesone or more of a alumina, a surfactant, a fibrous material, a setretarder, and a set accelerator, and combinations thereof.
 26. Theproduct of claim 10 including adding an effective amount of water toachieve a pressable, castable, pumpable, or sprayable consistency of therefractory composition and for creating a hydrate phase of theC_(n)A_(x).
 27. The product of claim 26 wherein the refractorycomposition comprises a calcium aluminate cement.
 28. The product ofclaim 26 wherein the sprayable refractory composition comprises apumpable first component comprising the refractory composition and adispersant, and the water, and optionally a second component comprisinga flocculating agent, wherein the optional second component is added tothe pumpable first component in amounts effective to form a sprayablerefractory composition.
 29. The product of claim 28 including employingin combination with the dispersants one or more rheology additives. 30.The product of claim 29 wherein the rheology additives are one or moreof a boric acid retarder, a citric acid retarder, and a lithiumcarbonate, and combinations thereof.